Vaccine safety

Safe development and manufacturing

Strict procedures are followed when vaccines are made. Before a vaccine can be approved for use it goes through a long testing process by international scientists to check that it is safe, and that it works. This process usually takes several years and includes trials on people who volunteer to use it. Before a vaccine is approved for supply in New Zealand the manufacturer must demonstrate its quality, that it works well and that it is safe to the satisfaction of Medsafe, a division of the Ministry of Health.

Medsafe’s evaluation is performed to internationally defined standards and is based on data from clinical trials.

The gold standard for clinical trials includes three phases:

  • Phase 1: Small numbers of people take the same vaccine using different methods of delivery and/or dosage. Assesses safety and immune response.
  • Phase 2: Uses larger numbers of people and compares new treatments with a placebo. Continues to assess safety and immune response.
  • Phase 3: Large, randomised trial(s) to test the effect of a new vaccine against a control group. This phase tests safety and efficacy, which is the percentage of people that the vaccine protects from catching the disease.

Ongoing monitoring

Once a vaccine has been introduced to New Zealand, the Centre for Adverse Reactions Monitoring (CARM) at Otago University records reactions reported after vaccination.

Vaccinators are asked to report all clinically significant events following vaccination to CARM. Parents may also report online or by ringing CARM on 03 479 7247. The information provided to CARM by doctors, nurses and parents will assist in identifying those children who should receive follow-up immunisation in a controlled environment, such as a hospital.

Medsafe reviews reports about adverse events from all medicines, and if they detect a safety concern, they can provide updated advice to health professionals about the safe use of the medicine, restrict its use or in rare circumstances recall a medicine.  For more information about this process see Medicines Safety Monitoring.

Any serious reactions may also be recorded on the National Immunisation Register (NIR).

Parents should contact their doctor or Healthline (phone 0800 611 116) if they are worried about their child following immunisation.

Vaccine administration

Everyone who is able to administer vaccines in New Zealand has undergone specialised training, whether they are practice nurses, general practitioners, midwives or pharmacists.  Training ensures that vaccinators can provide emergency treatment, handle vaccines safely and effectively, and communicate accurately and effectively with patients to gain informed consent. 

Vaccine administration errors occur rarely, for example where one vaccine is mistakenly given in place of another, or an additional dose of a vaccine is given. These do not usually cause any harm to patients, but are taken very seriously and reported to CARM. The Health and Disability Commissioner can investigate complaints about administration errors. Changes to vaccination processes, resources or packaging are made when problems are identified, to reduce the chance of future administration errors.

All vaccines in use in New Zealand come in single-dose vials, except for the Bacillus Calmette-Guerin (BCG) vaccine, which is given to at-risk children to protect against tuberculosis, and comes in 10-dose vials.  BCG vaccinators receive special training to administer this vaccine. 

For detailed information about vaccinator training, see the Immunisation Handbook and Immunisation Advisory Centre website

Vaccine storage

Most vaccines must be stored and transported at a constant temperature of between 2 and 8 degrees Celsius to ensure they remain safe and effective. Immunisation providers must store vaccines in a pharmaceutical fridge, with two systems of recording temperatures. The process for tracking storage temperature is called the cold chain. Temperatures are checked and logged regularly so that any vaccines stored outside the recommended temperature are identified before they can be administered to patients. Cold chain processes are regularly checked and audited.

For detailed information about cold chain processes, see National Immunisation Programme cold chain management.

Further information

For more information about the safety and effectiveness of immunisation, and how common and severe the diseases it protects against are, the Immunisation Handbook and the following resources are useful.


National Centre for Immunisation Research and Surveillance, Australia

Centre for Disease Control and Prevention, USA

American Academy of Pediatrics

Institute for Environmental and Scientific Research (ESR)


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